/Engine/Source/Runtime/Engine/Classes/Engine/LevelStreamingGCHelper.h
Static array of levels that should be unloaded
static [TArray](API\Runtime\Core\Containers\TArray)< [TWeakObjectPtr](API\Runtime\Core\UObject\TWeakObjectPtr)< [ULevel](API\Runtime\Engine\Engine\ULevel) > > LevelsPendingUnload;